Constructivist literature has become increasingly prominent in the area of special education. The nature of constructivism and its relevance and limitations for students with special needs is discussed, as is the importance of appropriate research in determining the efficacy of instructional interventions. A search of the literature into the efficacy of constructivism for students with special needs in K-12 settings revealed a predominance of descriptive and discussion-based research and very limited experimental research. The limited existing experimental research indicates that constructivist instructional approaches may have circumscribed applications in special education. Specifically, they may be appropriate to applications for students with learning difficulties in areas such as science education. Nevertheless, there are major methodological and interpretative problems that undermine confidence in the existing body of research. These problems include an absence of adequate procedural reliability data, interventions that often involve teaching single or very small groups of students, and conditions that do not approximate regular classrooms. There is also evidence suggesting that constructivist approaches may be inappropriate and ineffective for students with intellectual disabilities. The need for considerable caution and extensive further research in this area is evident, in light of the ready adoption of constructivism in schools and the increase of constructivist literature.